INTRODUCTION

The Standard Malaysian Name for the timber of Coelostegia spp., Durio spp., Kostermansia sp. and Neesia spp. (Bombacaceae). Vernacular names applied include durian (Peninsular Malaysia, Sabah and Sarawak) with various epithets as well as other localised names too numerous to list here. Major species include Coelostegia borneensis, C. griffithii; Durio carinatus, D. grandiflorus, D. graveolens, D. lowianus, D. malaccensis, D. oxleyanus, D. singaporensis, D. wyatt-smithii, D. zibethinus; Kostermansia malayana; Neesia altissima, N. kostermansiana, N. malayana and N. synandra. The sapwood is almost white in Durio, pale yellow in Neesia and light orange-yellow in Coelostegia and is sharply defined in Durio and Neesia but only moderately sharply defined in Coelostegia, from the heartwood, which is pink-brown, grey-brown, brown with a red tinge or light orange-brown.

Also known as Durian (Brunei); Bengang, Durian, Durian hantu, Ki bengang and Sibengang (Indonesia); Durian and Stemmed-durian (Philippines); and Chang haek and Turian (Thailand).

DENSITY

Durian is a Light Hardwood with a density of 420-865 kg/m3 air dry.

NATURAL DURABILITY

Four species of durian were tested for their durability by the standard graveyard test and the results indicated that durian timbers are not durable if exposed to natural Malaysian weather conditions. The test samples with dimension of 50 mm x 50 mm x 600 mm were destroyed in a relatively short period of time, for example, Neesia altissima (1.5 years), Durio lowianus (1.7 years) and Coelostegia griffithii (1.5 years) (Mohd Dahlan Jantan et. al., 1987). However, it should be stressed here that the above durability ratings are only applicable to Malaysia where termites are common and fungi are very active throughout the year. In temperate countries, however, the threat of ‘infestation’ by both insects and fungi are very much reduced and the durability of the timber will be greatly extended.

PRESERVATIVE TREATMENT

It is easy to treat with preservatives.

TEXTURE

Texture is moderately coarse to coarse and even in Neesia but uneven in Durio and Coelostegia, with straight to slightly interlocked grain.

STRENGTH PROPERTIES

The timber falls into Strength Group C (Engku, 1988b) or SG 6 (MS 544:Part 2:2001).

Strength Properties of Durian

Species

Test Condition

Modulus of Elasticity (MPa)

Modulus of Rupture (MPa)

Compression parallel to grain (MPa)

Compression perpendicular to grain (MPa)

Shear Strength (MPa)

C. griffithii

Green

14,300

71

38.5

4.00

8.3

Air dry

15,800

95

53.9

5.65

9.2

D. oxleyanus

Green

10,600

55

27.4

2.96

7.2

Air dry

11,700

74

39.0

4.14

8.0

N. altissima

Green

8,600

51

26.5

2.59

5.9

Air dry

9,500

65

32.5

2.72

6.8

MACHINING PROPERTIES

It is easy to slightly difficult to resaw and easy to difficult to cross-cut. Planing is easy to moderately easy and the planed surface is smooth to moderately smooth and sometimes even rough, especially in the radial boards.

Machining Properties of Durian

Species

Test Condition

Sawing

Planing

Boring

Turning

Re-sawing

Cross Cutting

Ease of planing

Quality of finish

Ease of boring

Quality of finish

Ease of turning

Quality of finish

C. griffithii

Green

fairly easy

difficult

easy

moderately smooth

slightly difficult

moderately smooth

Air dry

slightly difficult

difficult

moderately easy

moderately smooth

slightly difficult

moderately smooth

slightly difficult

moderately difficult

D. oxleyanus

Green

easy

easy

easy

smooth

easy

fairly smooth

Air dry

easy

easy

easy

smooth

easy

fairly smooth

easy

rough

D. zibethinus

Green

easy

easy

easy

moderately smooth

easy

moderately smooth

Air dry

N. altissima

Green

easy

easy

easy

rough, especially radial

easy

rough

Air dry

NAILING PROPERTY

Nailing property ranges from good to excellent.

AIR DRYING

Seasoning properties vary according to species, which are summarised as follows:

Species

Time to air dry (months)

Remarks

13 mm

thick boards

38 mm

thick boards

C. griffithii

2.5

3.5

Moderately fast drying; moderate staining; slight dimensional movement and splits; shrinkage low.

D. oxleyanus

3

4

Fairly slow drying; moderate insect attack; slight cupping; shrinkage high.

N. altissima

1.5-2

3-4

Moderately fast drying; slight end-checking and splitting; average shrinkage.

KILN-DRYING

Kiln Schedule D is tentatively recommended for the drying of durian timbers. The timber of durian can be kiln-dried at a moderately fast rate with only slight twisting except for the timber of D. oxleyanus, which requires up to 1.5 months to dry boards of 70 mm x 127 mm with variable lengths. It is also recommended that sawn timber of durian be air dried for a minimum period of 2 weeks before being kiln-dried to save on cost.

Kiln Schedule D

Moisture Content (%)

Temperature

(Dry Bulb)

Temperature

(Wet Bulb)

Relative Humidity (%) (approx.)

° F

° C

° F

° C

Green

105

40.5

101

38.0

85

60

105

40.5

99

37.0

80

40

105

40.5

96

35.5

70

35

110

43.5

97

36.0

60

30

115

46.0

97

36.0

50

25

125

51.5

101

38.0

40

20

140

60.0

105

40.5

30

15

150

65.5

112

44.5

30

SHRINKAGE

Shrinkage varies according to species, which are summarised as follows:

Species

Shrinkage (%) (Green to air dry)

Radial

Tangential

C. griffithii

1.3

1.6

D. oxleyanus

2.4

4

N. altissima

1.3

2.4

MOVEMENT IN SERVICE

The movement of seasoned timber is classified under Type IV.

DEFECTS

The logs of all the timber producing species of the Bombacaceae are normally sound and free of defects except for a small area of sponginess around the pith, and damage by ambrosia and, occasionally, longicorn beetles. An area of 2 to 3 inches (51 to 76 mm) of sponginess has been observed in logs of Durio spp. and Neesia altissima but the compression failures usually associated with this type of defect have not been encountered. The timber of species of Durio contains abundant starch, and, although not very susceptible to sap stain, is liable to attack by all forms of wood-boring insects and to heavy infestation by Lyctus. On the other hand, the limited amount of material of N. altissima that has been examined contained very little starch and was attacked only by a small number of pin-hole borers.